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• 


UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.   106 


SPRAYING    APPLES 

Relative  Merits  of  Liquid  and  Dust  Applications 


BY  CHARLES  S.  CRANDALL 


URBANA,  ILLINOIS,  FEBRUARY,  1906 


SUMMARY  OF  BULLETIN  No.  106. 

1.  Measures  of  repression  directed  against  insects  and  fungi  must  aim 
at  prevention  rather  than  cure.  Page  208. 

2.  Spraying  with  liquid  has  been  a  universal  practice.     The  introduc- 
tion of  the  dry  process  raised  questions  regarding  the  relative  merits  of  the 
two  methods.  Page  209. 

3.  Experiments  in  1903,  with  schedule  and  diagram.  Page  212. 

4.  Differences  between  plats  treated  by  the  two  methods  were  apparent 
in  July  and  became  more  marked  as  the  season  advanced.     Liquid-sprayed 
trees  held  the  foliage  perfectly,  while  the  dust-sprayed  and  check  trees  lost 
nearly  all  leaves  by  September  1.     Fruit  of  dust-sprayed  and  check  trees  was 
practically  ruined  by  apple  scab  and  fruit;  blotch,  while  fruit  of  liquid-sprayed 
trees  was  comparatively  free  from  blemish.  Page  214. 

5.  Apple  scab  developed  as  much  without  restraint  on  dust-spraj'ed  as 
on  check  trees,  but  was  almost  perfectly  controlled  on  liquid-sprayed  trees. 

Page  216. 

6.  Tabulation  of  percentages  of  fruit  affected  with  apple  scab,  showing 
the  greater  effectiveness  of  liquid-spraj-   and  also  the  increase  of  benefit 
following  increased  number  of  applications.  Page  217. 

7.  Experiments  in  1904.  Page  219. 

8.  Foliage  fell  or  remained  upon  the  trees  according  to  the  treatment 
given,  as  it  did  in  1903.  Page  220. 

9.  Examples  of  the  grading  of  the  fruit  from  different  plats.     Page  227- 

10.  Additional  experiments  in  1905.  Page  233. 

11.  Results  in  1905  the  same  as  in  1903  and  1904  and  equall}'  decisive. 

Page  233. 

12.  Dust  spra3r  is  52%  cheaper  than  liquid  spray  and  it  is  easier  to  trans- 
port about  the  orchard,  but  value  can  not  depend  upon  these  two  factors. 

Page  237. 

13.  Thoroughness  of  application  with  either  method  of  spra3'ing  depends 
upon  the  men  who  supply  the  force  and  direct  the  deliver}-.  Page  238. 

14.  CONCLUSION.  Page  239. 

Merits  of  the  two  methods  must  rest  upon  efficienc}1  in  prevent- 
'       ing  the  ravages  of  fungi  and  in  killing  insects.  Page  239. 

The  experiments  detailed  have  extended  over  three  seasons.  They 
have  included  an  aggregate  of  424  trees;  147  sprayed  with  liquid;  167 
spra}red  with  dust,  and  110  control  trees.  The  number  of  apples 
handled  totals  372,726.  Results  were  the  same  in  all  orchards  in  all 
seasons.  Page  239. 

The  conclusion  is  f  ull}'  warranted  that  the  dust  spray  is  absolutely 
ineffective  as  a  preventive  of  prevailing  orchard  fungi,  and  that  it  is 
much  less  effective  as  an  insect  remedy  than  is  the  liquid  method  of 
applying  arsenites.  Page  240. 


SPRAYING    APPLES 


Relative  Merits  of  Liquid  and  Dust  Applications 


BY  CHARLES  S.  CRANDALL 


No  problem  is  of  more  direct  and  vital  interest  to  the  owner 
of  an  apple  orchard  than  that  relating  to  the  repression  of  injurious 
insects  and  fungi.  Borers,  twig-girdlers,  canker,  and  blight  attack 
the  trees.  Canker  worms  and  scab  defoliate.  The  fruit  is  infested 
with  curculio  and  codling  moth,  or  is  destroyed  by  bitter  rot,  or  is 
defaced  and  rendered  unsalable  by  apple  scab  and  blotch. 

It  has  been  the  experience  in  every  fruit-producing  region  that 
pioneer  orchards  were  free  from  injurious  insects  and  fungi  dur- 
ing their  earlier  years ;  that,  later,  injuries  by  insects  or  fungi,  or 
both  began  to  appear  and  that,  as  orchard  areas  increased,  the  inju- 
ries multiplied  until  crops  were  ruined  unless  protected  by  the  per- 
sistent application  of  means  of  repression.  Except  for  small  isolated 
regions  in  the  far  west  the  country  has  passed  the  pioneer  stage  in 
fruit-growing.  For  most  sections  the  business  is  comparatively 
old ;  pioneer  plantings  have  disappeared  and  present  orchards  be- 
long to  the  second,  or  even  to  the  third  generation  of  orchards. 
Insect  enemies  and  injurious  fungi  have  had  time  to  become  widely 
disseminated  and  thoroughly  established. 

It  may  be  assumed  that  these  pests  are  here  permanently  and  in 
the  planning  of  any  fruit-producing  enterprise  they  must  be  con- 
sidered and  dealt  with  as  one  of  the  important  factors. 

These  orchard  enemies  are  not  equally  abundant  or  equally  de- 
structive in  all  sections,  nor  are  the  attacks  uniform  in  all  seasons. 
Most  of  them  range  in  cycles ;  there  are  periods  of  excessive  abun- 
dance followed  by  years  of  comparative  scarcity,  but  the  year  of 
abundance  of  one  insect  may  be  the  year  of  scarcity  of  another ;  the 
cycles  of  different  species  vary  in  length,  so  that  it  is  hardly  possible 
to  predict  which  enemies  will  preponderate  in  any  particular  year. 

Weather  conditions  play  an  important  part  and  in  great  measure 
govern  the  abundance  and  destructiveness  of  both  insects  and  fungi. 
It  is  evident  from  the  nature  of  the  injuries  inflicted  by  both  insects 
and  fungi  that  these  injuries  can  not  be  cured.  Leaves  that  have 
been  eaten  can  not  be  restored;  the  worm  that  gains  access  to  the 

207 


208  BULLETIN  No.  106.  [February, 

interior  of  a  fruit  is  safe  from  molestation  except  by  destruction  of 
the  fruit.  Vegetative  portions  of  most  fungi  are  within  the  tis- 
sues of  the  plant  beyond  reach  of  destruction  except  by  destroying 
the  containing  tissues.  It  is  therefore  perfectly  evident  that  meas- 
ures of  repression  directed  against  both  insects  and  fungi  must  be 
entirely  preventive  and  not  curative.  Full  appreciation  of  this  fact 
is  essential  to  the  successful  and  economical  application  of  reme- 
dies and  it  is  suggested  that  every  orchardist  should  make  himself 
familiar  with  the  life  histories  of  the  insects  and  fungi  he  may  find 
it  necessary  to  combat ;  there  is  satisfaction  in  knowing  these  things 
and  the  knowledge  is  essential  to  intelligent  action.  It  is  true  that 
full  information  is  not  at  hand  for  all  insects  or  all  fungi,  but  the 
more  common  and  most  destructive  are  pretty  well  understood,  and 
information  regarding  them  is  easily  obtainable.  The  more  com- 
plete the  knowledge  of  the  enemy  the  easier  it  is  to  plan  a  campaign 
and  the  greater  is  the  possibility  of  success.  Some  orchardists  ap- 
preciate the  truth  of  this  proposition  and  are  successful  in  practice. 
There  are  others  who  do  not  appreciate  it,  whose  ideas  of  the  orchard 
enemies  they  would  fight  are  very  hazy  and  whose  haphazard  prac- 
tice is  not  successful. 

Although  insects  and  fungi  have  been  doing  enormous  injury 
to  fruit  crops  for  many  years,  it  is  only  within  a  very  recent  period 
that  means  of  repression  have  been  reduced  to  anything  like  effect- 
ive system.  Many  years  ago  in  the  older  fruit  regions  numerous 
substances  or  compounds  that  by  reason  of  strong  odors,  caustic  or 
poisonous  action,  were  supposed  to  be  destructive  to  insects,  were 
applied  to  plants  in  a  small  way,  either  in  the  form  of  dry  powder, 
or  in  liquid  form  sprinkled  on  with  a  garden  syringe.  Sometimes 
these  applications  were  reported  successful,  but  more  often  they 
failed  to  accomplish  the  desired  result.  Arsenic  in  some  form  was 
used  quite  early,  but  its  very  poisonous  nature  raised  objections  which 
were  difficult  to  overcome  and  there  was  the  additional  disadvantage 
that  it  invariably  proved  injurious  to  foliage.  The  advent  of  the  Colo- 
rado Potato  Beetle  brought  compounds  of  arsenic  into  common  use. 
It  was  necessary  to  kill  the  beetles,  the  arsenic  compounds  proved 
most  effective  and  soon  they  were  in  great  demand.  No  ill  effects 
were  experienced ;  people  became  accustomed  to  the  use  of  the  vari- 
ous compounds  and  from  successful  use  on  potatoes,  applications  to 
all  kinds  of  plants  for  the  repression  of  all  kinds  of  chewing  insects 
followed  in  easy  sequence. 

All  the  arsenic  compounds  were  more  or  less  injurious  to  foliage 
and  this  was  a  great  objection  to  their  use.  In  1889  Professor  Gil- 
lette found  that  the  addition  of  lime  to  compounds  of  arsenic  greatly 


1&06.]  SPRAYING  APPLES.  209 

reduced  the  injury  to  foliage.  This  discovery  was  quickly  adopted 
in  practice  and  marks  the  general  acceptance  of  arsenic  in  some  of 
its  compounds  as  the  best  destroyer  of  chewing  insects. 

In  the  fall  of  1882  the  discovery  was  accidently  made  by  Pro- 
fessor Millardet  at  Bordeaux,  France,  that  a  mixture  of  copper  sul- 
phate solution  and  lime  applied  to  foliage  would  prevent  develop- 
ment of  grape  mildew.  This  discovery  led  Professor  Millardet  to 
inaugurate  experiments  in  1883  which  were  continued  until,  in 
1885,  he  gave  out  the  first  definite  formula  for  compounding  copper 
sulphate  and  lime,  forming  what  has  since  been  known  as  Bordeaux 
mixture.  This  first  formula  was  soon  modified  considerably  as  to 
proportion  of  ingredients  and  its  use  was  extended  until  it  came  to 
be  accepted  as  the  sovereign  remedy  for  most  of  the  fungi  attacking 
fruit  plants.  The  first  means  of  applying  Bordeaux  mixture  were 
very  crude  and  attention  was  soon  turned  to  improvement  in  this 
direction.  When  comparison  is  made  between  the  appliances  in 
use  today  and  those  in  use  fifteen  or  twenty  years  ago,  it  becomes, 
evident  that  the  evolution  of  methods  of  application  has  been  rapid. 

Spraying  has  become  a  permanent  factor  in  fruit-growing  and  is 
recognized  as  one  of  the  essentials  of  good  orchard  practice.  The 
development  of  spraying  has  been  rapid,  but  perfection  has  by  no 
means  been  reached.  There  is  yet  much  to  be  learned  regarding 
the  relative  efficiency  of  various  formulae  and  many  improvements 
are  to  be  expected  in  the  mechanical  means  of  application  and  in  de- 
tails of  practice  that  will  diminish  the  cost  and  increase  the  effect- 
iveness of  spraying.  By  common  consent  water  has  been  the 
-medium  used  for  distributing  the  copper  and  arsenic  compounds. 
Spraying  with  liquid  has  been  the  universal  practice.  A  few  years 
ago  it  was  suggested  that  the  compounds  used  in  spraying  should 
be  applied  in  a  dry  way,  using  dry-slaked  lime  as  the  conveyor  and 
dusting  the  trees  by  means  of  a  strong  air  blast.  Naturally  the  two 
methods,  spraying  with  liquid,  and  dusting,  suggested  questions 
regarding  the  relative  merits  of  the  two.  Which  is  the  cheaper? 
Which  the  more  easily  applied  ?  Which  is  more  effective  ? 

These  are  practical  questions  and  correct  answers  are  of  im- 
portance to  those  engaged  in  fruit-growing.  The  demands  upon  the 
Experiment  Station  for  definite  answers  have  been  numerous  enough 
to  show  a  widespread  interest  in  the  matter. 

Some  of  the  men  propounding  these  questions  made  more  or  less 
extensive  tests  of  the  two  methods  in  their  own  orchards  in  1902 
and  preceding  years.  As  a  result  of  these  tests  some  gave  approval 
to  the  dusting  process,  some  gave  unqualified  condemnation,  while 
Others  were  in  doubt.  All  were  anxious  for  more  light  regarding 


210  BULLETIN  No.  100. 

this  matter.  Accessible  printed  information  on  the  subject  is  not 
extensive.  There  are  some  articles  in  horticultural  periodicals 
lauding  the  dusting  process  as  the  only  panacea  for  orchard  troubles, 
other  articles  holding  that  only  liquid  spray  is  effective,  and  still 
others  that  discuss  the  subject  pro  and  con  without  definite  com- 
mendation of  either  method.  There  have  been  no  reports  of  definite 
and  careful  experiments  testing  the  two  methods  upon  contiguous 
blocks  of  trees  with  adjacent  checks. 

Statements  of  results  which  are  based  upon  general  impressions 
of  any  given  treatment,  especially  when  no  control  trees  are  main- 
tained for  comparison,  do  not  satisfy;  the  mind  of  the  observer 
may  lean  a  little  in  one  direction  or  the  other,  and,  perhaps  uncon- 
sciously, he  fails  to  overcome  that  natural  tendency  to  see  what  he 
wishes  to  see.  Such  reports  always  leave  openings  for  question 
and  doubt. 

In  order  to  compare  the  efficiency  of  two  methods  of  treatment 
of  orchard  trees  for  insect  injury  and  the  ravages  of  fungous  dis- 
eases, the  methods  in  question  must  be  tested  side  by  side  under  con- 
ditions as  nearly  alike  as  it  is  possible  to  make  them.  There  must 
also  be  proper  control  trees  which  shall  be  conditioned  as  are  the 
other  trees  in  everything  except  the  particular  treatment  under  in- 
vestigation. Observations  must  be  frequent,  records  full,  careful 
and  continuous,  and  observed  phenomena  must  be  correctly  inter- 
preted. This  implies  much  labor,  the  exercise  of  patience,  and  the 
use  of  good  judgment,  but  results  obtained  in  any  other  way  do  not 
warrant  definite  conclusions. 

EXPERIMENTS  UNDERTAKEN 

In  response  to  the  popular  demand  for  information  the  horti- 
cultural department  of  the  Experiment  Station  undertook  certain 
experiments  designed  to  test  the  relative  efficiency  of  the  two  meth- 
ods of  applying  spray  materials.  The  experiments  were  commenced 
in  1903  in  the  orchard  of  Mr.  W.  C.  Reed  four  miles  south  of  Olney. 
This  orchard  was  chosen  because  conveniently  near  other  experi- 
ments then  in  progress  and  because  it  offered  a  fairly  even  block  of 
one  variety  that  had  never  been  treated  with  any  kind  of  spray.  The 
five  west  rows  of  this  orchard  containing  a  total  of  108  trees  were 
used  in  the  experiment.  The  trees  of  the  two  west  rows  were  at 
this  time  18  years  old,  those  in  the  other  rows  17  years  old.  There 
was  no  appreciable  difference  due  to  this  difference  in  age,  but  all 
the  trees  at  the  north  end  of  the  block  were  noticeably  larger 
than  were  the  trees  of  equal  age  at  the  south  end.  This  variation 
in  size  was  most  probably  due  to  some  difference  in  the  soil.  The 


1906. \ 


SPRAYING  APPLES. 


211 


ORCHARD  OF  MR.  W.  C.  REED. 
Experiments  testing  the  relative  merits  of  liquid  spray  and  dusting. 


Plat  No.  1— Liquid 
Check  row  No.  1 

Plat  No.  2— Dust 

Check  row  No.  2 

Plat  No.  3— Liquid 
Check  row  No.  3 

Plat  No.  4— Dust 

Check  row  No.  4 

Plat  No.  5— Liquid 
Check  row  No.  5 

Plat  No.  6— Dust 

Check  row  No.  6 

Plat  No.  7— Liquid 
Check  row  No.  7 

Plat  No.  8— Dust 


O  O 

0  0 


0 


0 


0 


0 


0 


0 

0 
0 

0 
O 

0 
0 

O 
0 

0 
0 

O 
0 

0 
O 

0 
O 

O 
O 

W- 


O 
O 

O 
O 

O 
O 

0 
0 

0 
0 

0 
O 

0 

0 

O 
O 

O 
O 

O 
O 

0 
0 

O            0            O 
0 

0 
O 

0 
O 

O 
0 

O 
0 

O 
O 

O 
O 

N 

A 


212  BULLETIN  No.  106. 

larger  size  of  the  trees  at  the  north  end  brought  them  into  close  con- 
tact so  that  the  lower  branches  interlaced.  Some  pruning  was  done  to 
correct  this,  but  only  enough  to  admit  free  passage  in  cultivating 
and  spraying.  The  block  was  divided  into  eight  plats  of  two  rows 
each,  and  seven  rows,  one  between  each  two  plats,  as  control  or 
check  trees.  Plats  i,  3,  5,  and  7  were  scheduled  for  treatment  with 
Bordeaux  mixture  applied  in  liquid  form,  while  the  alternate  plats 
numbered  2,  4,  6,  and  8  were  to  be  treated  with  Bordeaux  applied 
dry,  as  dust.  Owing  to  vacancies  the  number  of  trees  in  the  plats 
was  not  quite  uniform,  but  the  total  in  each  set  was  the  same, 
namely  38,  with  32  trees  in  the  seven  check  rows.  The  arrangement 
of  plats  is  shown  in  the  diagram,  page  211. 

The  plan  of  operations  decided  upon  was  to  treat  the  four  plats 
numbered  i,  3,  5,  and  7  with  Bordeaux  mixture  and  Paris  green, 
using  what  is  known  as  the  "standard  formula,"  which  is,  4  pounds 
of  copper  sulphate,  4  pounds  of  lime,  %  pound  of  Paris  green  and 
50  gallons  of  water,  and  to  treat  the  alternate  plats  numbered  2,  4, 
6,  and  8  with  the  "Dry  Bordeaux  and  Paris  green"  preparation 
manufactured  and  sold  by  the  "Dust  Sprayer  Manufacturing  Com- 
pany," of  Kansas  City,  Missouri.  This  material  was  to  be  applied 
with  one  of  the  "Cyclone"  machines  made  by  the  same  company. 
The  prearranged  schedule  of  applications  was  as  follows : 
Plat  No.  i  liquid  and  Plat  No.  2  dust.  Three  applications. 

i — as  buds  are  bursting. 

2 — after  petals  have  fallen. 

3 — one  week  later. 
Plat  No.  3  liquid  and  Plat  No.  4  dust.  Five  applications. 

r — as  buds  are  bursting. 

2 — after  "petals  have  fallen. 

3 — one  week  later. 

4 — date  intermediate  between  application  No.  3  and  July  10. 

5— July  10. 
Plat  No.  5  liquid  and  Plat  No.  6  dust.    Seven  applications. 

i — as  buds  are  bursting. 

2 — after  petals  have  fallen. 

3 — one  week  later. 

4 — on  date  intermediate  between  application  No.  3  and  July  10. 

5— July  10. 

6 — July  24. 

7 — August  7. 
Plat  No.  7  liquid  and  Plat  No.  8  dust.    Eight  applications. 

i — as  buds  are  bursting. 

2 — after  petals  have  fallen, 


1906+] 


SPRAYING  APPLES 


213 


3 — one  week  later. 

4 — on  or  about  June  15. 

5 — ten  days  later  or  June  25. 

6 — ten  days  later  or  July  5. 

7 — ten  days  later  or  July  15. 

8 — ten  days  1  iter  or  July  25. 

The  seven  check  rows  containing  32  trees  were  to  receive  no 
spray  whatever. 

Owing  to  weather  conditions,  the  first  application  planned  to  be 
given  as  buds  were  bursting  was  omitted  and  the  first  application 
was  made  just  after  the  petals  had  fallen.  With  this  exception  the 
schedule-  was  followed  closely  and  the  plats,  instead  of  receiving 
3,  5,  7,  and  8  applications  as  planned,  received  only  2,  4,  6,  and  7 
applications  respectively.  The  actual  dates  of  application  were  as 
follows : 


Liquid  plats. 

Dust  plats. 

No.  1. 

No.  3. 

No.  5. 

No.  1. 

No.  2. 

No.  4. 

No.  6 

No.  8. 

April  30  

1 

1 

o 

3 

3 
3 

3 

4 

5 

5 
5 

5 

5 
5 
« 

7 

1 

1 
1 
1 

1 
7 

1 

2 

2 

2 

4 
4 
4 

4 
4 

6 
(5 
(5 

6 

6 
ti 
6 

8 
8 

8 
8 
8 

8 
8 

1 

May  1    

May  8         

June  6  

June  15  

June  25  

July  6..  

July  10  

July  15  

July  25  

August  1  

Times  sprayed.  . 

In  making  the  first  application  the  liquid  was  applied  late  in  the 
afternoon  of  April  30  and  the  dust  early  in  the  morning  on  May  i. 

Subsequent  applications  were  completed  the  same  day,  and  the 
practice  was  to  apply  the  dust  very  early  in  the  morning,  between  the 
hours  of  4  and  6,  while  the  dew  was  still  on  and  before  wind  arose ; 
the  liquid  applications  following  later  in  the  day.  In  applying  both 
liquid  and  dust  preparations  great  care  was  exercised  to  do  the  work 
in  the  most  thorough  manner  possible.  While  effort  was  made  to 
confine  the  applications  to  the  trees  for  which  they  were  intended, 
there  was,  on  two  or  three  occasions,  some  unavoidable  drift  of 
material  to  adjoining  check  trees.  This  was  especially  the  case  in 
applying  dust,  but  it  is  not  thought  that  this  drift  was  sufficient  to 
influence  greatly  the  results. 

It  was  the  intention  to  gather  all  fallen  apples  at  frequent  in- 


214  BULLETIN  No.  106.  [February, 

tervals  and  record  the  defects  found  on  them,  but  because  of  insuffi- 
cient assistance  for  all  work  at  hand,  it  was  found  impossible  to  do 
this  and  no  fallen  fruit  was  gathered  and  examined  until  Septem- 
ber i ,  except  that  all  fallen  apples  affected  with  bitter  rot  were  col- 
lected and  recorded  from  and  after  July  27.  These  fallen  apples 
having  bitter  rot  were  gathered  July  27  and  28,  August  8,  August 
20  and  August  27. 

The  first  of  September  a  general  gathering  of  all  fallen  apples 
was  made;  this  included  also  those  fruits  having  bitter  rot.  This 
procedure  was  repeated  September  n  to  14  and  again  October  16 
to  23. 

The  final  picking  of  fruits  from  the  trees  was  commenced  Octo- 
ber 16.  The  plan  followed  was,  first  to  gather  the  fallen  fruit 
of  one  plat  or  one  check  row,  examine  each  apple  and  make  the 
record ;  then  pick  the  fruit  of  that  plat  or  check  row,  examine  and 
record  in  the  same  manner.  Because  this  plan  was  followed,  the 
dates  of  the  last  gathering  of  fallen  apples  and  the  dates  of  final 
picking  run  along  together  from  October  16  to  October  23.  On 
this  latter  date  the  work  was  completed. 

APPARENT  EFFECTS  OF  THE  APPLICATIONS 

Foliage. — During  the  month  of  July  differences  between  plats 
became  apparent.  It  was  particularly  noted  by  all  who  visited  the 
orchard  that  the  foliage  of  the  trees  upon  the  liquid  sprayed  plats 
was  of  darker  color  and  generally  of  more  healthy  appearance  than 
the  foliage  of  dust  sprayed  and  check  trees.  This  difference  in  ap- 
pearance of  foliage  was  due,  in  the  main,  to  apple  scab,  which  con- 
tinued to  develop  on  the  leaves  of  dust  sprayed  and  check  trees, 
while  its  growth  had  been  in  great  part  arrested  or  prevented  on 
leaves  of  the  liquid-sprayed  trees. 

Early  in  August  leaves  began  falling  from  dust-sprayed  and 
check  trees  and  by  the  first  of  September  only  a  few  scattered  leaves 
remained  upon  the  trees.  By  the  first  of  October,  these  trees  had 
entirely  lost  their  foliage  and  were  as  bare  as  in  mid-winter.  Up  to 
the  first  of  October  very  few  leaves  had  fallen  fr6m  the  trees  of  the 
liquid-sprayed  plats.  The  foliage  was  practically  intact  and  as 
green  as  in  early  summer.  Most  of  the  foliage  was  still  on  the  trees 
when  the  work  of  the  season  was  completed  on  October  23. 

The  whole  line  of  plats  was  in  full  view  from  the  much  traveled 
highway  on  the  west  side  of  the  orchard  and  the  marked  foliage  dif- 
ferences attracted  attention  from  all  who  passed.  There  was  con- 
stant demand  for  explanation  of  the  observed  differences  and  infor- 
mation concerning  the  work,  viewed  as  an  illustration  of  direct 


SPRAYING   APPLES. 


results  from  two  methods  of  treatment  as  compared  with  no  treat- 
ment, became  widely  disseminated. 

Fruit. — Differences  in  foliage  were  not  the  only  differences 
observable  on  the  plats.  From  casual  examination  of  the  fruit  upon 
the  trees,  it  was  at  once  evident  that  apple  scab  and  fruit  blotch 
had  developed  freely  on  the  dust  sprayed  and  check  trees.  Apples 
on  these  trees  were,  almost  without  exception,  small,  deformed, 
roughened  and  cracked  by  the  advanced  development  of  scab,  and 
were  totally  worthless.  They  appeared  in  strong  contrast  with  the 
larger,  smooth,  clean-skinned  fruit  from  the  liquid-sprayed  trees. 

The  quantity  of  fruit  borne  by  the  trees  was  small,  but  consider- 
ably greater  than  in  most  orchards  in  the  neighborhood.  The  crop 
was  estimated  at  about  one-fifth  of  a  normal  full  crop.  The  trees 
produced  abundant  bloom,  but  the  cold  wet  weather  which  pre- 
vailed through  the  blooming  period,  culminating  in  a  hard  "freeze" 
May  i,  killed  the  greater  portions  of  the  young  fruits.  However, 
enough  apples  remained  upon  the  trees  to  warrant  continuing  the 
experiment  according  to  the  plan.  The  number  of  apples  recorded 
from  all  trees  was  17,297.  Of  these,  13,162  or  76.09  percent  were 
windfalls  and  4,135  or  23.91  percent  were  picked  from  the  trees. 
The  distribution  by  numbers  and  percentages  between  the  two  sets 
of  plats  and  the  check  rows  was  as  follows : 


Windfalls. 

Picked. 

Number. 

Percent. 

Number. 

Percent. 

Total. 

Liquid  sprayed  4  plats  —  38  trees 
Dust  sprayed  4  plats—  38  trees.  . 
Check  1  rows  —  32  trees  

6,223 

3,366 
3,573 

68.04 
84.85 
85.39 

2,923 
601 
till 

31.96 
15.15 
14.61 

9,146 
3,967 
4,184 

17,297 

It  will  be  noted  that  more  than  half  or  52.88  percent  of  the  total 
number  of  apples,  came  from  the  38  trees  sprayed  with  liquid,  and 
that  the  rest  were  nearly  equally  divided  between  the  dust-sprayed 
and  the  check  trees;  the  former  having  nearly  23  percent  of  the 
total  and  the  latter  a  little  more  than  24  percent.  Further,  it  is  seen 
that  the  percentage  of  windfalls  is  considerably  higher  for  the 
dust-sprayed  and  check  trees  than  it  is  for  the  liquid-sprayed  trees. 
Had  the  same  proportion  of  fruit  remained  on  the  dust-sprayed  trees 
as  was  picked  from  the  liquid-sprayed  trees,  we  should  have  picked 
from  the  dust-sprayed  trees  1,581,  instead  of  601  apples;  more  than 
two  and  a  half  times  as  many,  or  nearly  50  percent  of  the  total  num- 
ber of  apples  borne  by  the  38  trees.  In  the  same  way,  the  check 
trees  would  have  yielded  1,678  apples,  instead  of  611,  or  about  forty- 
seven  percent  of  the  total  number  of  apples  from  the  check  trees. 


216  BULLETIN  No.  106.  [February, 

APPLE  SCAB 

The  differences  in  amount  of  fruit  gathered  from  the  two  sets 
of  plats,  as  given  above,  were  not  due  to  any  differences  in  size  of 
the  trees,  or  to  differences  in  the  amount  of  fruit  originally  on  the 
trees,  but  may  be  directly  charged  to  the  development  of  apple  scab. 
This  fungus  appeared  early  in  the  season,  and  with  favorable  con- 
ditions developed  rapidly.  On  trees  treated  with  liquid  Bordeaux 
mixture,  its  development  was  almost  entirely  prevented,  but  on 
dust-sprayed  and  check  trees,  it  continued  to  grow  and  spread. 
The  apples  were  attacked  when  very  small  and  a  large  proportion 
of  them  were  so  badly  injured  that  they  dropped  from  the  trees  in 
June  and  early  July,  decayed,  and  disappeared.  Many  apples  that 
were  injured  in  somewhat  less  degree  remained  longer  on  the  trees, 
but  before  picking  time,  fell  in  such  numbers  as  to  increase  greatly  the 
percentage  of  windfalls.  Apple  scab  appeared  to  grow  as  much  with- 
out restraint  upon  the  dust-sprayed  trees  as  it  did  upon  the  check 
trees ;  no  difference  between  the  two  could  be  detected. 

For  the  fallen  apples  recorded,  the  percentage  marked  by  scab 
was  more  than  four  times  greater  for  the  dust-sprayed  than  for  the 
liquid-sprayed  trees,  and  for  the  picked  fruit  the  difference  in  favor 
of  liquid-spray  was  still  more  marked.  With  all  fruits,  not  only 
was  the  percentage  affected  greater  for  the  dust-sprayed  trees,  but 
the  degree  of  injury  to  individual  fruits  was  very  much  greater. 
Liquid-sprayed  fruits  recorded  as  affected  by  scab,  were,  in  great 
part,  marked  by  small  spots  only,  while  fruits  so  recorded  from  the 
dust-sprayed  and  check  trees,  generally,  had  nearly  the  whole  sur- 
face covered  by  the  fungus.  These  fruits  were  small,  deformed, 
cracked,  and  of  no  value. 

All  apples  gathered,  both  picked  and  windfalls  were  separately 
examined  and  record  made  of  the  injury  by  diseases  and  insects. 
Record  was  also  kept  of  those  fruits  attacked  by  bitter  rot,  but  this 
has  no  bearing  upon  the  relative  merits  of  the  two  kinds  of  spray, 
because  this  disease  appeared  upon  only  a  few  trees  scattered  through 
the  block.  Bitter  rot  was  confined  to  trees  upon  which  it  had  ap- 
peared in  previous  seasons. 

In  the  following  tabulation  are  given  the  percentages  of  fruit 
affected  by  apple  scab  and  these  percentages  are  arranged  by  plats 
in  order  to  show  the  results  as  influenced  by  the  number  of  applica- 
tions. The  figures  in  the  first  two  columns  cover  all  fruits,  both 
picked  and  windf alien;  the  other  columns  contain  percentages  de- 
rived from  the  picked  fruit  only. 


1006 \  SPRAYING  APPLES. 

PERCENTAGES  OF  FRUIT  AFFECTED  BY  APPLE  SCAB. 


217 


All  fruits. 

Picked  fruits  only. 

Liquid. 

Dust. 

Check. 

Liquid. 

Dust. 

Check. 

Plats  1  and  2 
Times  sprayed  2  

9.94 
8.53 
3.70 

3.39 
7.51 

54.98 
40.61 

38.90 

49.03 
48.05 

40.37 

2.09 
1.14 

0.00 

0.00 

.89 

85.26 
84.62 
75.81 

91.73 
85.  6B 

82.49 

Plats  3  and  4 
Times  sprayed  4  

Plats  5  and  6 
Times  sprayed  6  

Plats  7  and  8 
Times  sprayed  7  '.  .  .  . 

All  plats  

The  efficiency  of  Bordeaux  mixture  in  liquid  form  as  a  prevent- 
ive of  apple  scab  is  plainly  shown  by  the  percentages  here  given. 

For  the  four  liquid-sprayed  plats  only  7.51  percent  of  all  the 
fruits,  windfalls  and  picked,  were  marked  by  scab,  as  against  48.05 
percent  of  the  fruits  from  the  four  dust-sprayed  plats.  Considering 
picked  fruits  only,  we  have  .89  percent  for  the  liquid-sprayed  plats 
as  compared  with  85.69  percent  for  the  dust-sprayed  plats.  A  fur- 
ther difference,  not  shown  by  the  figures,  is  found  in  the  fact  that 
individual  fruits  from  the  liquid-sprayed  trees  were  much  less  in- 
fected by  the  disease  than  were  those  from  dust-sprayed  trees. 

The  significance  of  an  increased  number  of  applications  of  liquid 
Bordeaux  mixture  is  shown  in  the  regularly  decreasing  percentages 
of  infected  fruits  from  Plat  No.  i  to  Plat  No.  7  as  the  applications 
increased  from  2,  to  7.  This  is  especially  noticeable  in  the  picked 
fruit  column  where  for  plats  5  and  7,  with  6  and  7  applications,  the 
scab  was  completely  controlled.  It  is  equally  evident,  from  the  per- 
centages given,  that  dry  Bordeaux  was  wholly  ineffectual  as  a 
preventive  of  this  disease. 

Apple  scab  was  the  most  prevalent  disease,  it  was  thoroughly 
established  in  the  orchard  and  its  early  development  did  snot  yield 
readily  and  entirely,  even  to  well-applied  liquid  Bordeaux  mixture. 
To  this  disease  is  ascribed  the  loss  of  many  small  apples  early  in  the 
season  and  it  is  almost  entirely  responsible  for  the  early  loss  of 
foliage  by  all  trees  except  those  sprayed  with  liquid  Bordeaux  mix- 
ture. 

FRUIT  BLOTCH. 

The  fungus  passing  under  the  name  of  Fruit  Blotch  spreads  in 
irregular,  sooty  black  patches  on  the  surface  of  the  apple ;  it  arrests 
development,  causes  cracking  of  the  skin  and  is  a  conspicuous  blem- 
ish. This  fungus  does  not  appear  until  mid-summer  and  does  not 


218 


BULLETIN  No.  106. 


[February 


reach  its  period  of  most  rapid  development  until  the  cooler  weather 
of  September.  Distribution  of  the  fungus  in  the  orchard  was  not 
uniform ;  it  was  much  more  abundant  on  Plats  7  and  8  at  the  south 
end  of  the  block  than  elsewhere  and  there  were  marked  differences 
between  trees  of  the  same  plat.  Some  were  very  badly  infected, 
others  were  comparatively  free.  The  fungus  developed  most  abun- 
dantly and  rapidly  on  fruits  already  marked  by  apple  scab,  but  also 
attacked  other  fruits  on  which  no  scab  appeared.  The  following 
tabulation  gives  percentages  of  all  fruits  infected  and  also  the  per- 
centages derived  from  the  picked  fruit. 

PERCENTAGES  OF  FRUIT  AFFECTED  BY  FRUIT  BLOTCH. 


All  fruits. 

Picked  fruits  only. 

Liquid. 

Dust. 

Check. 

Liquid. 

Dust. 

Check.; 

Plats  1  and  2 
Times  sprayed  2  

3.33 

7.28 
5.93 

16.46 
7.50 

33.65 
48.66 
55.62 

47.08 
43.23 

34.35 

3.93 
9.78 
6.56 

14.32 

9.07 

52.99 
57.34 
51.61 

29.66 

48.25 

44.03 

Plats  3  and  4 
Times  sprayed  4  

Plats  5  and  6 
Times  sprayed  6  

Plats  7  and  8 

All  Dlats.  . 

The  percentages  here  given  are  decidedly  in  favor  of  liquid 
Bordeaux,  although  they  do  not  indicate  so  perfect  control  as  was 
obtained  over  apple  scab.  This  is  probably  due  to  the  fact  that  spray- 
ing was  done  early  during  the  period  when  apple  scab  naturally  de- 
velops, while  with  the  fruit  blotch  much  of  the  infection  came  long 
after  the  last  spraying  was  done.  The  percentage  of  fruit  attacked 
on  Plat  No.  7  was  very  high  in  comparison  with  other  plats,  not- 
withstanding the  increased  number  of  applications.  This  was  due 
to  the  greater  abundance  of  the  fungus  on  that  plat  and  to  very  late 
infection  on  many  fruits.  This  late  infection  was,  on  most  fruits, 
very  slight ;  enough  to  indicate  the  presence  of  the  fungus,  but  not 
causing  serious  blemishes. 

The  dust  spray  proved  no  more  effective  in  controlling  fruit 
blotch  than  in  preventing  apple  scab. 

CODLING  MOTH 

Neither  liquid  nor  dust  spray  proved  very  effective  this  season 
against  this  insect.  Considering  all  fruits,  the  gain  of  liquid  Bor- 
deaux over  the  check  trees  was  6.35  percent  and  the  gain  of  liquid 
over  dust  was  7.79  percent  or,  calculating  from  picked  fruit  only, 
the  liquid  shows  a  gain  over  check  of  23.84  percent  and  a  gain 


1906.]  SPRAYING  APPLES.  2li) 

dust  of  22.91  percent.  The  small  percentages  of  benefit  here  shown 
are  ascribed  to  weather  conditions.  Heavy  rains,  which  were  of 
frequent  occurrence  during  the  spraying  period  washed  away  the 
Paris  green,  leaving  no  protection  against  this  insect. 

CURCUUO 

The  percentages  of  fruits  marked  by  curculio  show  but  trifling 
benefits  from  either  form  of  spray.  For  all  apples  of  all  plats,  13.68 
percent  of  liquid-sprayed  fruits  were  marked  by  curculio,  16.76  per- 
cent of  dust-sprayed  fruits  and  14.65  percent  of  fruits  from  check 
trees.  For  the  picked  fruit  a  slightly  greater  gain  is  shown,  but  too 
small  to  be  regarded  as  a  commendation  of  spraying.  It  was  shown 
in  Bulletin  No.  98  that  the  curculio  feeds  anywhere  on  the  fruit  and 
that  perfect  protection  would  mean  the  complete  covering  of  the 
surface  with  poison.  This  can  not  be  done  in  a  practical  way  and, 
while  it  was  shown  that  under  favorable  circumstances  from  20  per- 
cent to  40  percent  of  benefit  might  be  obtained  by  spraying,  the 
benefit  is  so  commonly  far  below  this  that  spraying  is  not  highly 
commended  as  a  remedy  for  curculio. 

SUMMARY  OF  THE  WORK  IN  1903 

Summarized  results  for  the  season  of  1903  were  decisive;  the 
differences  between  liquid  and  dust-sprayed  plats  were  so  marked 
as  to  leave  no  doubt  in  the  minds  of  the  most  casual  observers. 

Liquid  Bordeaux  proved  its  efficiency  in  controlling  the  domin- 
ant fungi,  while  dust  spray  was  entirely  ineffective ;  so  much  so  that 
no  differences  were  apparent  between  dust-sprayed  and  check  trees 
in  retention  of  foliage  or  in  character  of  fruit. 

Results  in  preventing  insect  injury  were  not  markedly  success- 
ful, owing,  in  part,  at  least,  to  unfavorable  weather  conditions,  but 
such  benefit  as  was  attained  was  on  the  side  of  liquid  applications. 

EXPERIMENTS  IN  1904 

To  add  the  experience  of  another  season,  to  augment  the  data 
already  gathered  regarding  the  relative  merits  of  the  two  methods 
of  applying  spray  materials  and  to  verify  the  results  of  1903,  the 
work  was  repeated  in  the  W.  C.  Reed  orchard  and  duplicated  in 
the  orchard  of  Mr.  John  Sawdon  near  Griggsville  in  Pike  county. 

THE  REED  ORCHARD  IN  1904 

In  the  Reed  orchard  the  same  trees  were  used  and  the  schedule 
of  applications  was  the  same  as  that  used  in  1903.  Spring  weather 
was  favorable,  no  omissions  were  necessary  and  the  applications  for 


220 


BULLETIN  No.  106. 


[Februwy, 


the  season  of  1904  were  3,  5,  7,  and  8,  instead  of  2,  4,  6,  and  7.  A 
new  "Cyclone"  dust  machine  was  purchased  and  used;  prepared 
dry  Bordeaux  and  Paris  green  was  obtained  fresh  from  the  factory 
and  all  applications  were  made  in  the  most  thorough  manner.  The 
quantity  of  apples  borne  by  the  trees  was  over  six  times  as  great 
as  in  1903,  a  practically  full  crop,  and  in  general  the  conditions  were 
favorable  for  a  fair  test  of  the  two  methods  of  spraying. 

Foliage. — In  the  Reed  orchard  the  foliage  fell  or  remained  upon 
the  trees,  according  to  the  treatment  given,  just  as  it  did  in  1903. 

Differences  between  the  liquid-sprayed  trees  and  the  others  were 
apparent  in  July  and  as  the  season  advanced  the  differences  became 
more  marked.  By  the  middle  of  September  the  dust-sprayed  trees 
and  the  check  trees  were  almost  entirly  denuded,  while,  on  the 
liquid-sprayed  trees,  the  dark  green,  healthy  leaves  continued  to  per- 
form their  functions  until  the  close  of  the  season.  The  cause  of  Jhe 
loss  of  foliage  by  the  dust-sprayed  and  check  trees  was,  as  in  1903, 
the  unrestricted  development  of  apple  scab. 

The  accompanying  illustrations,  plates  i,  2,  and  3  serve  to  show 
in  some  degree  the  foliage  differences  between  liquid-sprayed,  dust- 
sprayed  and  check  trees  as  they  appeared  on  October  27,  1904. 

Plate  4  shows  the  defoliated  condition  of  a  portion  of  the  or- 
chard east  of  the  plats.  No  applications  of  any  kind  had  been  made 
to  these  trees. 

Fruit. — Early  in  July  differences  in  the  appearances  of  the  fruit 
on  the  different  plats  became  apparent.  Fruit  on  liquid-sprayed 
trees  was  smooth  and  comparatively  free  from  the  blemishes  which 
were  conspicuous  on  fruit  of  dust-sprayed  and  check  trees.  These 
differences  increased  as  the  season  advanced;  they  attracted  the 
immediate  attention  of  all  who  visited  the  orchard. 

The  following  tabulation  gives  the  total  number  of  apples  from 
each  set  of  plats  and  the  relation  by  numbers  and  percentages  of 
windfallen  and  picked  apples. 

RELATION  OF  WINDFALLEN  AND  PICKED  APPLES  BY  NUMBERS 
AND  PERCENTAGES. 


Windfallen. 

Picked. 

Number. 

Percent. 

Number. 

Percent. 

Total. 

Liquid  sprayed,  4  plats,  38  trees 
Dust  sprayed,  4  plats,  38  trees 
Check,  not  sprayed,  1  rows,  32 
trees  

14677 
15,205 

14,585 
44,467 

32.21 
42.62 

47.30 
39.64 

30,896 
20,474 

16,248 
67,618 

67.79 
57.38 

52.70 
60.33 

4f>..-)7:! 
35,679 

30,833 
112,085 

Totals  

1906.  ] 


SPRAYING  APPLES. 


221 


DH 

cw 

p 

s 

0? 


222 


BULLETIN  No.  106. 


[February, 


1906.1 


SPRAYING  APPLES. 


223 


224 


BULLETIN  No.  106. 


[February, 


1006.] 


SPRAYING  APPLES. 


225 


Comparing  the  percentages  here  given  with  those  of  1903  a 
marked  difference  is  apparent.  While  in  1903  only  31.96  percent  of 
the  total  number  of  apples  produced  by  the  liquid-sprayed  trees  re- 
mained upon  the  trees  until  picking  time,  in  1904  the  same  trees 
held  67.79  percent.  There  is  the  same  difference  regarding  other 
plats.  The  dust  plat  figures  are  15.15  percent  for  1903  and  57.38 
percent  for  1904.  For  the  check  trees  14.61  percent  for  1903  and 
52.70  percent  for  1904.  The  greatly  increased  amount  of  fruit 
and  the  better  weather  conditions  of  spring  are  accountable  for  these 
differences. 

APPLE  SCAB 

Apple  scab  was  as  abundant  as  in  1903.  The  number  of  apples 
was  nearly  six  and  one  half  times  as  many  as  in  1903  and  the  per- 
centage affected  by  the  disease  was  considerably  higher  than  last 
year.  This  is  due  largely  to  a  development  of  the  disease  late  in  the 
fall  and  so  long  after  the  last  spray  was  applied  to  plats  I,  2,  3,  and  4 
that  the  Bordeaux  had  been  almost  completely  washed  from  the 
fruit.  However,  this  late  infection  did  not  result  in  serious  blem- 
ishes on  liquid-sprayed  fruit,  merely  small,  and  mostly  very  small, 
discolored  spots  on  the  surface,  not  sufficiently  developed  to  roughen 
the  epidermis. 

The  percentages  for  all  fruits  affected  were  as  follows : 

PERCENTAGES  OF  FRUIT  MARKED  BY  APPLE  SCAB. 


Liquid  sprayed,  percent 
of  scabby  fruit. 

Dust  sprayed,  percent  of 
scabby  fruit. 

Plats  1  and  2 
Times  sprayed  3  

63.03 

88  27 

Plats  3  and  4 
Times  sprayed  5  

28.50 

82.14 

Plats  5  and  6 
Times  sprayed  1  

18  20 

63  62 

Plats  1  and  8 
Times  sprayed  8  

8.47 

73.40 

Check,  no  spray 83.17^ 

This  tabulation  includes  all  apples  marked  in  the  slightest  way 
by  apple  scab,  but  it  conveys  no  adequate  idea  of  the  difference  in 
appearance  between  the  fruit  from  the  liquid-sprayed  and  that  from 
the  other  trees.  The  liquid-sprayed  fruit  generally  appeared  clean 
and  smooth  as  seen,  either  on  the  trees  or  on  the  sorting  tables. 
Fruit  from  the  dust-sprayed  and  check  trees  was  smaller  and  much 
discolored  and  disfigured  by  the  large  spots  of  scab.  In  recording 
the  fruit  blemishes,  a  division  was  made  between  those  apples 
marked  only  by  few  and  small  spots  of  scab  and  those  having  many 


BULLETIN  No.  106. 


FIGURK  1.— FRUIT  FROM  TREE  No.  8  OF  PLAT  No.  5.  SPRAYED  WITH  LIQUID. 


FIGURE  2.— FRUIT  FROM  TREE  No.  1  OF  PLAT  No.  6.    SPRAYED  WITH  DUST. 


FIGURE  3. — FRUIT  FKOM  TREE  No.  1  OF  CHECK  Row  No.  2.    NOT  SPRAYED. 


1906.]  SPRAYING  APPLES.  227 

and  large  spots;  this  divisiqn  places  over  90  percent  of  the  liquid- 
sprayed  apples  in  the  slightly  marked  class,  leaving  less  than  10  per- 
cent recorded  as  much  marked.  Dust-sprayed  fruit  was  nearly 
equally  divided  between  the  two  groups,  and  with  the  fruit 
from  the  check  trees  a  little  more  than  half  were  in  the  badly 
scabbed  class. 

By  comparing  plat  No.  I  which  had  63  percent  of  the  fruit 
marked  by  scab  with  plat  No.  7  which  showed  only  8.47  percent  of 
infected  fruit  it  is  plainly  shown  that  the  later  applications  of  Bor- 
deaux mixture  prevented  late  infection. 

The  accompanying  figures  are  fair  photographic  representations 
of  the  manner  in  which  fruit  from  the  different  sets  of  plats  graded. 

Figure  i  shows  the  picked  fruit  from  tree  No.  8  of  plat  No.  5 
sprayed  seven  times  with  liquid  Bordeaux  and  Paris  green. 

The  total  number  of  apples  was  1009,  divided  as  follows : 

3J4  bushels  No.  i 440  apples 

3      bushels  No.  2 488    " 

l/2  bushel  culls 81    " 

Figure  2  shows  the  fruit  from  tree  No.  i  of  plat  No.  6  sprayed 
seven  times  with  Bordeaux  and  Paris  green,  as  dust. 

The  total  number  of  apples  was  1,102  divided  as  follows : 

5      only  No.  1 5  apples 

4^  bushels  No.  2 682    " 

\y*  bushels  culls 415    ' 

Figure  3  shows  the  fruit  from  tree  No.  i  of  check  row  No.  2, 
not  sprayed. 

The  total  number  of  apples  was  1049  divided  as  follows: 

o      No.  i o  apples 

1 1/2  bushels  No.  2 308    ' 

zy-t  bushels  culls 741 

• 

FRUIT  BLOTCH 

The  percentages  of  fruit  blotch  on  fruit  from  liquid-sprayed 
trees  ranged  from  3.59  percent  on  plat  No.  7  which  was  sprayed 
eight  times,  to  16.54  percent  on  plat  No  i  which  was  sprayed  three 
times.  Percentages  on  dust-sprayed  trees  ranged  from  51.67  percent 
to  74.18  percent  and  the  check  trees  showed  51.39  percent  of  infected 
fruit. 

The  fungus  yielded  quite  readily  to  applications  of  liquid  Bor- 
deaux, but  dust  applications  were  entirely  inefficient  in  controlling  it. 


228 


BULLETIN  No.  106. 


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ORCHARD  or  JOH«  SAWDOM  OR/GCSVILLE:  ILL 
FIGURE  4. 


1906.]  SPRAYING  APPLES.  220 

EXPERIMENTS  NEAR  GRIGGSVILLE 

At  Griggsville  the  work  was  conducted  in  connection  with  expe- 
riments for  control  of  curculio  which  were  then  in  progress.  Six 
rows  containing  136  trees  were  included  in  the  experiment.  Four 
plats  aggregating  67  trees  were  sprayed  with  dust  and  four  contain- 
ing 47  trees  were  sprayed  with  liquid.  Five  rows  across  the  block, 
located  between  plats  and  containing  22  trees  were  not  sprayed 
and  served  as  control  trees  for  comparison  with  the  treated  plats. 

The  four  plats  to  be  treated  with  dust  were  purposely  made 
somewhat  larger  than  the  others  in  order  to  admit  of  division  for 
testing  two  machines  and  the  prepared  dust  as  made  by  two  com- 
panies. One  half  of  each  dust  plat  was  scheduled  for  spraying  with 
the  "Cyclone"  machine  and  the  prepared  Bordeaux  as  made  by  the 
"Dust  Sprayer  Manufacturing  Company"  of  Kansas  City,  Missouri ; 
the  other  half  with  the  "Whirlwind"  machine  and  the  "Dry  Bor- 
deaux" as  manufactured  by  the  "Kiser  Whirlwind  Duster  Manu- 
facturing Company"  of  Stanberry,  Missouri. 

After  thorough  trial  the  "Whirlwind"  machine  was  abandoned 
as  wholly  inefficient.  The  division  of  plats  was  maintained,  but 
the  two  kinds  of  dust  were  applied  with  the  one  machine,  the 
"Cyclone,"  which  did  the  work  in  a  satisfactory  manner.  At  the 
close  of  the  season  there  was  no  appreciable  difference  between  the 
divisions  of  these  plats;  each  plat  is  tabulated  as  a  whole  and  noth- 
ing further  need  be  said  of  this  division.  The  accompanying  dia- 
gram, Figure  4,  shows  the  location  and  arrangement  of  the  plats. 

Foliage — Differences  in  foliage  between  liquid-sprayed  trees  on 
the  one  hand,  and  dust-sprayed  and  check  trees  on  the  other,  the 
same  differences  that  were  observed  in  the  Reed  orchard,  were  ap- 
parent in  the  Sawdon  orchard,  but  not  to  quite  the  same  extent. 
Liquid-sprayed  trees  held  the  foliage  as  perfectly,  but  dust-sprayed 
and  check  trees  did  not  lose  the  leaves  quite  as  rapidly  and  completely 
as  did  the  corresponding  trees  in  the  Reed  orchard.  This  is  ascribed, 
in  part,  to  a  less  vigorous  attack  of  apple  scab  and,  in  part,  to  dif- 
ferences in  varieties.  In  the  Reed  orchard  the  trees  are  all  Ben 
Davis,  in  the  Sawdon  orchard  the  varieties  are  Milam  and  Wealthy. 
The  Milam  trees  held  the  foliage  rather  better  than  did  the  Ben 
Davis,  and  the  Wealthy  held  the  foliage  better  than  either  of  the 
others. 

Fruit — Of  the  trees  included  in  the  block,  the  Wealthy  bore  a 
very  heavy  crop,  the  Milam  a  fair  crop.  The  total  number  of  ap- 
ples recorded  was  132,707  and  the  distribution  between  liquid  plats, 
dust  plats  and  check  rows  is  shown  by  numbers  and  percentages  for 
both  picked  and  vvindfallen  fruits  in  the  following  table. 


230  BULLETIN  No.  106.  [Fetrvary, 

NUMBERS  AND  PERCENTAGES  OF  WINDF ALLEN  AND  PICKED  APPLES. 


Windfallen. 

Picked. 

Number. 

Percent. 

Number. 

Percent. 

Total. 

Liquid  sprayed  4  plats     

23,568 
43,509 
10,435 
77,512 

48.64 
63.09 
68.26 
58.41 

24,893 
25,450 
4,852 
55,195 

51.36 
36.91 
31.74 
41.59 

48,461 
68,959 
15,287 
132.707 

Dust  sprayed  4  plats  

Check  5  rows     

Totals  

The  fact  that  the  percentages  of  fruit  harvested  from  the  trees 
are  not  as  high  as  for  the  Reed  orchard  is  explained  by  the  operation 
of  additional  agencies  that  largely  increased  the  number  of  dropped 
apples  in  the  Sawdon  orchard.  Apple  scab  was  about  equally  abun- 
dant in  the  two  orchards.  Curculio  was  very  much  more  abundant 
in  the  Sawdon  orchard  and  is  responsible  for  the  fall  of  many 
apples.  To  the  work  of  this  insect  may  be  added  the  action  of  high 
winds,  early  in  October,  which  brought  to  the  ground  a  considerable 
portion  of  the  Milam  apples.  However,  spraying  helped  to  retain 
the  fruit  upon  the  trees  as  is  shown  by  comparison  of  the  percentages 
given,  although  full  benefit  of  the  applications  is  in  a  measure  ob- 
scured by  the  necessity  of  including  with  the  windfalls  the  apples 
brought  down  by  wind  and  those  falling  from  attacks  of  curculio, 
an  insect  for  which  spraying  is  not  an  effective  remedy.  Comparing 
the  percentages  of  picked  fruit,  it  is  found  that  the  dust-sprayed  plats 
show  a  gain  over  the  check  trees  of  14  percent  and  the  liquid- 
sprayed  a  gain  of  38.20  percent.  Apple  scab  attacked  a  propor- 
tionately greater  number  of  apples  in  the  Sawdon  orchard  than  in 
the  Reed  orchard,  but  the  injury  to  individual  fruits  was  usually 
less. 

In  general  appearance  the  apples  from  the  Sawdon  orchard  were 
better  than  those  from  the  Reed  orchard,  mainly  because  of  the  en- 
tire absence  of  fruit  blotch.  This  fungus  on  account  of  its  dark 
color  and  its  action  in  cracking  the  fruit  does  more  to  render  apples 
unsightly  than  any  other  fungus,  and  when  it  makes  an  attack 
jointly  with  apple  scab  the  destructive  action  is  complete. 

The  percentages  of  fruit  marked  by  scab  in  the  Sawdon  orchard 
range  from  56  to  68  percent  for  the  liquid-sprayed  plats ;  86  percent 
to  96  percent  for  the  dust-sprayed  plats  and  96  percent  for  the  check 
trees.  These  percentages  are  higher  than  for  the  fruit  in  the  Reed 
orchard  and  do  not  indicate  so  much  benefit  from  increased  number 
of  applications  of  liquid  Bordeaux. 

Separating  the  fruit  marked  by  scab  into  two  groups,  one  very 
slightly  marked,  the  other  showing  large  spots,  82  percent  of  the 


1906.~\  SPRAYING  APPLES.  231 

liquid-sprayed  fruits,  43  percent  of  the  dust-sprayed  fruits  and  31 
percent  of  the  fruit  from  check  trees  fall  into  the  slightly  marked 
group.  This  leaves  18  percent  of  liquid-sprayed  fruits  in  the  much 
marked  group,  which,  considering  the  fact  that  the  orchard  had  not 
been  sprayed  in  previous  years,  is  a  fairly  low  percentage. 

As  in  the  Reed  orchard,  it  required  the  record'  from  individual 
fruits  to  bring  out  any  difference  between  fruit  from  the  dust-sprayed 
trees  and  the  check  trees.  Observation  of  the  fruit  on  the  trees  and 
on  the  tables  did  not  discover  that  there  was  any  difference.  Liquid- 
sprayed  fruits,  however,  were  very  different  in  appearance  from 
those  on  dust-sprayed  and  check  trees.  They  were  larger,  smoother, 
and  in  every  way  more  desirable. 

CODLING  MOTH 

This  insect  was  moderately  abundant  and  the  sprays  applied 
were  fairly  successful  in  controlling  it.  The  fruit  from  check  trees 
showed  17.29  percent  infested;  from  dust-sprayed  trees  10.45  Per~ 
cent,  and  from  liquid-sprayed  trees  6.53  percent.  Computing  the 
gain  of  sprayed  trees^over  the  unsprayed  trees,  the  dust-sprayed  fruit 
shows  gain  over  the  check  of  39.56  percent.  Liquid-sprayed  fruit 
shows  gain  over  the  check  of  62.23  percent.  In  the  same  way  the 
gain  of  liquid  spray  over  the  dust  spray  is  37.51  percent. 

CURCUUO 

The  abundance  of  curculio  and  the  relative  efficiency  of  the  two 
methods  of  spraying  is  shown  in  the  following  percentages.  Of 
fruits  from  check  trees  93.76  percent  were  punctured  by  curculio. 
The  percentage  for  the  dust-sprayed  trees  was  81.09,  and  for  the 
liquid-sprayed  55.53,  or  a  gain  of  dust-sprayed  over  check  trees  of 
13.51  percent,  of  liquid-sprayed  trees  over  check  trees  of  40.77  per- 
cent and  of  liquid-sprayed  trees  over  dust-sprayed  trees  of  31.52 
percent. 

During  the  progress  of  the  experiments  at  Griggsville  and 
Olney,  many  orchard  owners,  and  others  interested,  visited  the  or- 
chards and  inspected  the  work.  The  differences  between  plats  were 
so  marked  and  the  results  of  the  different  applications  so  evident  to 
the  eye  that  all  visitors  obtained  distinct  impressions  of  the  relative 
merits  of  the  two  methods  of  treatment  and  were  particularly  im- 
pressed with  the  practical  benefits  to  be  derived  from  the  right 
application  of  Bordeaux  mixture  in  liquid  form. 

October  10,  just  before  the  final  picking  of  Milam  apples  began, 
a  party  of  twelve,  consisting  of  the  Advisory  Committee  and  others 


232 


BULLETIN  No.  106. 


[February, 


from  different  parts  of  the  state  met  in  the  Savvdon  orchard  for  in- 
spection of  the  work.  On  this  occasion  the  suggestion  was  made 
and  acted  upon,  that  a  committee  of  disinterested  persons  be  ap- 
pointed to  select  average  samples  of  the  fruit  from  different  plats. 
This  committee  performed  the  assigned  duty  and  after  the  samples 
had  been  examined,  they  were  photographed,  sent  to  cold  storage 
and  exhibited  at  the  meeting  of  the  State  Horticultural  Society  at 
Bloomington  in  December.  Accompanying  the  samples  was  the 
following  explanatory  note : 

ORCHARD  OF  JOHN  SAWDON 

GRIGGSVILLE,  ILLINOIS,  October  10,  1904. 

This  is  to  certify  that  we,  the  undersigned,  have  this  day  selected  character- 
istic average  specimen  apples  from  each  of  the  several  plats  respectively  sprayed 
with — 

Bordeaux  and  Paris  green  dust. 
Liquid  Bordeaux  and  Paris  green  mixture. 
Checks — no  spray  whatever. 

These  collections  are  duly  labeled  and  correctly  represent  the  apples  as 
borne  on  these  trees.  We  were  selected  on  the  ground  as  a  committee  for  this 
purpose  by  Dr.  T.  J.  Burrill  of  the  University  of  Illinois.  The  experiments  were 
conducted  under  the  direction  of  the  Department  of  Horticulture  of  the  Agri- 
cultural Experiment  Station. 

(Signed)  W.  S.  PERRINE, 
H.  A.  ALDRICH, 
F.  D.  VORIS, 

A.   V.   SCHERMERHORN, 
C.    G.   WlNN, 

Committee. 

The  three  samples  of  apples  were  critically  examined  and  blem- 
ishes recorded  as  shown  below. 


Treatment. 

Number 
of 
apples. 

Curculio. 

Cod- 
lins 
moth. 

Other 
insect, 
injury. 

Apple 
scab. 

Perfect 
apples. 

Liquid  spray  >  

50 

14 

0 

1 

35 

8 

Dust  spray'.  

132 

103 

1 

3 

131 

0 

Check,  no  spray  

111 

108 

6 

24 

111 

0 

The  apples  were  collected  in  large  paper  sacks  and  the  sacks 
were  about  equally  full.  The  differences  in  number  of  fruits  are 
due  to  differences  in  size  of  individual  fruits. 

Stating  the  blemishes  in  percentages,  curculio  had  attacked  28 
percent  of  the  liquid-sprayed  apples,  78.03  percent  of  the  dust- 
sprayed  apples,  and  97.30  percent  of  the  apples  from  the  check  trees. 

For  codling  moth  the  percentages  are  0.76  for  dust-sprayed  fruits, 
5.40  for  check  tree  fruits,  with  no  work  of  this  insect  on  the  liquid- 
sprayed  fruits.  Various  other  insects  had  left  marks  on  2  percent 


J90G.\  SPRAYING  APPLES.  233 

of  the  liquid-sprayed  fruits,  on  2.27  percent  of  the  dust-sprayed  ap- 
ples and  on  21.62  of  the  apples  from  the  check  trees.  Apple  scab 
was  present  on  70  percent  of  the  liquid-sprayed  apples,  on  99.24 
percent  of  the  dust-sprayed  apples  and  on  100  percent  of  the  fruit 
from  check  trees. 

These  sample  apples  as  photographed  are  shown  in  Figure  5. 


FIG.  u.    REPRESENTATIVE  APPLES  FROM  CHECK  TREES,  DUST  SPRAYED, 
AND  LIQUID  SPRAYED  PLATS.    SAWDON  ORCHARD,  GRIGGSVILLE,  1904. 

ADDITIONAL  EXPERIMENTS  IN  1905 

The  results  obtained  in  the  experiments  of  the  two  seasons 
1903  and  1904  give  a  perfectly  plain  answer  to  the  question  of  the 
relative  efficiency  of  dust  spray  as  compared  with  liquid  spray,  but 
to  make  still  further  additions  to  the  data  already  gathered  and  to 
furnish  a  practical  demonstration  in  a  section  of  the  state  where  or- 
charding is  a  principal  business,  a  somewhat  less  extensive  experi- 
ment was  conducted  during  the  summer  of  1905  in  connection  with 
certain  bitter  rot  experiments  in  an  orchard  at  Clay  City. 

Six  plats  of  twelve  trees  each  were  used  in  the  work.  Two  plats 
were  sprayed  with  liquid  Bordeaux  and  Paris  green,  one  six  times, 
the  other  nine  times ;  two  plats  were  sprayed  with  prepared  dry 
Bordeaux  and  Paris  green  applied  as  dust,  one  six  times,  the  other 
nine  times,  and  two  plats  were  reserved  as  control  and  were  not 
sprayed. 

Foliage  of  the  trees  included  in  this  exeriment  behaved  exactly 
as  did  the  foliage  in  the  Reed  orchard  in  1903,  and  again  in  1904. 
Leaves  began  falling  from  dust-sprayed  and  check  trees  in  July, 
and  by  the  first  of  September  these  trees  were  entirely  defoliated, 
while  the  24  trees  sprayed  with  liquid  Bordeaux  retained  the  foliage 
perfectly.  The  cause  of  the  loss  of  foliage  from  dust-sprayed  and 
check  trees  was,  as  in  previous  seasons,  the  unchecked  development 
of  apple  scab. 


BULLETIN  No.  106. 


PLATE  5.— TREE  No.  10  OF  PLAT  No.  11.    CLAY  CITY  ORCHARD.    CHKCK, 
NO  SPRAY.    FROM  PHOTOGRAPH  SEPTEMBER  26,  1905. 


1906.'] 


SPRAYING  APPLES. 


235 


PLATE  fi. — TREE  No.  7  OF  PLAT  No.  13.    CLAY  CITY  ORCHARD.    SPRAYED 
WITH  DUST.    FROM  PHOTOGRAPH  SEPTEMBER  26,  1905. 


236 


BULLETIN  No.  106. 


[February, 


PLATE  7.— TREE  No.  8  OF  PLAT  No.  12.    CLAY  CITY  ORCHARD.    SPRAYED 
WITH  LIQUID.    FROM  PHOTOGRAPH  SEPTEMBER  26,  1905. 


1906.]  SPRAYING  APPLES.  237 

The  striking  contrast  between  defoliated  plats  and  green-leaved 
plats  was  at  once  observed  and  commented  upon  by  those  who  vis- 
ited the  orchard.  Many  sought  information  regarding  treatment 
given,  and  made  detailed  examinations  of  the  plats  from  which  con- 
clusions were  drawn  regarding  the  relative  merits  of  the  methods 
used. 

The  relative  condition  of  foliage  on  the  different  plats  is 
shown  by  plates  5,  6,  and  7  which  are  from  photographs  taken  on 
September  26. 

A  total  of  110,637  apples  were  produced  by  the  72  trees.  The 
two  check  plats  are  credited  with  30,717;  the  two  liquid-sprayed 
plats  with  46,842 ;  and  the  two  dust-sprayed  plats  with  33,078. 
Regarding  the  division  between  windfallen  and  picked  apples, 
50.68  percent  of  the  total  number  of  apples  produced  by  the  check 
trees  were  picked  from  the  trees.  For  the  liquid-sprayed  trees  the 
percentage  of  picked  fruit  was  79.10,  and  for  the  dust-sprayed  trees 
55.16.  The  computed  gain  in  picked  fruit  over  the  check  trees  is, 
for  the  dust-sprayed  trees  8.12  percent  and  for  the  liquid-sprayed 
trees  35.92  percent. 

No  differences  could  be  detected  between  the  fruit  of  dust- 
sprayed  trees  and  that  from  check  trees  in  the  amount  of  infection 
from  apple  scab;  both  lots  were  so  badly  infected  that  they  were  of 
no  value  except  as  evaporator  stock.  On  the  other  hand,  the  fruit 
from  the  liquid-sprayed  trees  was  very  little  marked  by  scab  and  the 
percentage  of  good  barreling  stock  was  high. 

The  results  of  this  last  experiment  were  as  decisive  as  any  ob- 
tained. They  were  so  plain  that  the  most  casual  observer  could  read 
them  at  a  glance  and  understand  their  meaning.  As  an  actual 
demonstration  of  the  relative  merits  of  dust  and  liquid  spray  the 
experiment  served  a  most  excellent  purpose.  It  did  more,  it  helped 
to  impress  orchard  owners  with  the  absolute  necessity  of  combating 
insects  and  fungi  and  pointed  out  the  successful  way. 

RELATIVE  COST 

Throughout  the  experiments  records  were  kept  of  the  amount 
of  labor  and  materials  used.  From  these  records  the  cost  of  one 
application  to  one  tree  is  computed  to  be  3.62  cents  for  the  liquid 
spray  and  2.38  cents  for  the  dust  spray.  The  dust  spray,  therefore, 
costs  1.24  or  52  percent  less  per  tree  than  the  liquid  spray.  In  other 
words,  six  applications  of  dust  can  be  made  for  a  trifle  less  than 
the  outlay  required  for  four  applications  of  liquid.  If  cost  were  the 
only  consideration,  liquid  spray  would  be  quickly  discarded  in 
favor  of  the  dust  spray,  but  in  considering  the  value  of  two  methods 


238  BULLETIN  No.  106.  [F<bnwrn, 

of  treatment,  relative  efficiency  must  take  precedence  over  relative 
cost.  The  labor  and  material  for  any  application  is  thrown  away 
unless  a  profit  is  returned  by  the  result  secured.  Any  material  ap- 
plied that  will  not  control  fungous  diseases  and  check  insect  ravages 
fails  of  its  purpose  and  is  costly  at  any  price. 

TRANSPORTATION 

Great  advantage  is  claimed  for  dust  spray  because  the  weight  to 
be  hauled  about  the  orchard  is  so  much  less  than  when  liquid  spray 
is  used.  It  is  true  that  the  dust  required  for  a  given  area  is  many 
times  lighter  than  the  liquid  required  for  the  same  area  and  is  much 
easier  to  transport,  but  this  contention  like  cost,  must  be  entirely 
subordinate  to  the  efficiency  of  the  application. 

THOROUGHNESS  OF  APPLICATION 

Advocates  of  dust  spray  claim  greater  certainty  of  thorough 
work,  that  is,  of  completely  covering  the  trees.  They  say  "the  dust 
is  carried  in  a  cloud  and  must  settle  over  the  most  remote  limbs  as 
well  as  on  those  near  at  hand."  There  is  little  force  in  this  argument 
because  there  is  the  same  possibility  of  carelessness  on  the  part  of 
workmen  in  applying  dust  that  there  is  in  applying  liquid. 

A  good  dust  machine  will  throw  a  cloud  of  dust,  if  worked  with 
sufficient  force  and,  if  there  is  no  wind  and  if  the  delivery  tube  be 
rightly  directed  it  may  and  will  be  distributed  over  the  trees.  In 
like  manner,  a  good  spray  pump  if  worked  with  sufficient  force  will, 
if  the  nozzle  be  properly  manipulated,  distribute  liquid  spray  to  all 
parts  of  trees.  Wind  is  as  much  against  even  distribution  of  dust 
as  it  is  against  even  distribution  of  liquid. 

With  elevated  platform  and  extension  rods,  as  now  commonly 
used  in  applying  liquid  spray,  it  is  entirely  possible  to  reach  all 
parts  of  orchard  trees,  but,  with  either  method  of  spraying,  whether 
distribution  is  even  or  not  depends  upon  the  men  who  supply  the 
force  and -who  direct  the  delivery. 

PERSONAL,  COMFORT  OF  WORKMEN 

Spraying,  at  best,  is  not  a  pleasant  operation.  The  irritant 
nature  of  the  lime  dust  is  especially  annoying  to  workmen,  for,  no 
matter  how  careful,  they  at  times  become  enveloped  in  a  cloud  of  it 
and  take  more  or  less  of  it  into  the  lungs.  Liquid  spray  is  often 
blown  into  the  faces  of  the  workmen  and  its  corrosive  action  upon 
the  skin  is  not  pleasant.  But  the  workmen  who  assisted  in  the 
station  experiments  were  unanimous  in  choosing  liquid  spraying  as 
the  least  disagreeable  of  the  two. 


woo.}  SPRAYING  APPLES.  239 

CONCLUSION 

Insects  and  fungi  injurious  to  fruit  crops  are  assumed  to  be  here 
as  a  permanent  fixture  and,  in  order  to  secure  marketable  fruit,  it  is 
absolutely  necessary  to  combat  the  pests  in  some  manner.  Thou- 
sands of  dollars  have  been  spent  experimentally  in  the  effort  to  de- 
termine which  of  all  the  remedies  suggested  could  be  relied  upon  to 
produce  the  best  results  at  least  cost. 

The  results  of  experiments  led  to  the  introduction  of  Bordeaux 
mixture,  applied  as  a  liquid  spray,  as  a  remedy  for  fungi  and  vari- 
ous forms  of  arsenic  as  remedies  for  chewing  insects. 

These  remedies  have  come  into  general  use  and,  while  fre- 
quently failing  to  give  perfect  satisfaction,  because  of  improper 
preparation,  careless  application,  or  too  frequent  downpours  of  rain, 
are  still  recognized  as  the  best  that  have  been  discovered  up  to  the 
present  time. 

The  introduction  of  dry  Bordeaux  mixture  applied  with  arse- 
nites  as  a  dust  spray  was  prompted  by  a  desire  to  decrease  the  cost 
and  labor  of  spraying.  It  does  both  of  these  things,  but  its  value 
can  not  rest  upon  cost  and  ease  of  application.  The  final  test  of 
value  is,  and  must  be,  efficiency  in  preventing  injury  from  fungi  and 
in  killing  insects. 

The  experiments  conducted  by  the  department  of  horticulture, 
testing  the  relative  efficiency  of  the  wet  and  dry  sprays  have  extended 
over  three  seasons ;  they  have  included  an  aggregate  of  424.  trees, 
147  of  which  were  sprayed  with  liquid,  167  with  dust,  and  no 
maintained  as  control  trees  which  received  no  spray.  The  number 
of  apples  produced  by  these  trees  totals  372,726.  These  fruits  were 
examined  individually  and  record  made  of  blemishes. 

The  experiments  have  been  reasonably  extensive,  they  have  been 
carefully  executed  and  the  conclusions  drawn  are  fully  warranted 
by  the  results  obtained. 

With  regard  to  the  effects  upon  foliage  the  results  were  identical 
in  all  orchards  and  in  all  seasons.  Trees  sprayed  with  liquid  Bor- 
deaux and  Paris  green  retained  their  foliage  in  healthy  working 
condition  throughout  the  season.  Dust-sprayed  and  check  trees 
may  be  placed  together  because  the  behavior  of  foliage  was  the 
same  in  both.  Leaves  began  falling  in  July  and,  in  early  Septem- 
ber, these  trees  were  practically  denuded.  This  loss  of  foliage  by 
dust-sprayed  and  check  trees  was  due  to  apple  scab,  against  which 
disease  the  dust  spray  was  entirely  ineffective.  The  effects  of  this 
loss  of  foliage  are  very  serious.  The  assimilatory  processes  of  trees 
are  active  in  proportion  to  the  working  leaf  surface ;  as  leaves  fall, 


240  BULLETIN  No.  106.  [February, 

these  processes  diminish  until  brought  to  a  stop  by  the  entire  loss  of 
foliage,  long  before  the  work  of  the  season  should  normally  end. 
The  fruit  is  starved,  does  not  approach  normal  size,  and  buds  for  the 
next  year  can  not  be  properly  developed. 

It  also  frequently  happens  that  under  the  stimulus  of  rains  and 
high  temperatures  in  October,  leaf  buds  of  the  defoliated  trees,  that 
normally  should  remain  dormant  until  spring,  unfold  and  expand  clus- 
ters of  new  leaves.  This  renewed  and  abnormal  activity  of  the  trees 
affects  fruit  buds  also;  a  considerable  portion  of  them  have  been 
observed  to  swell  and  some  expand  the  flowers.  All  this  is  greatly 
to  the  detriment  of  the  trees  and  fatal  to  the  prospective  crop  for 
the  next  year.  It  emphasizes  the  necessity  of  such  treatment  as  will 
retain  the  foliage  in  full  working  condition  until  the  end  of  the 
season. 

Compare  the  tree  shown  in  plate  8,  which  was  sprayed  six  times 
with  liquid  Bordeaux  and  Paris  green  with  the  tree  in  plate  9, 
which  was  not  sprayed.  The  difference  is  striking.  In  one  case  the 
foliage  of  the  season  is  intact  and  doing  full  work,  in  the  other,  not 
only  has  the  foliage  of  the  season  been  lost,  but  in  the  attempt  to 
repair  the  loss,  buds  that  should  have  remained  dormant  until  the 
next  spring  have  been  called  into  activity  and  have  put  forth  leaves. 

This  extra  draft  upon  the  resources  of  the  tree  impairs  vitality. 
The  tree  enters  the  winter  in  weakened  condition  and,  while  it  may 
survive,  is  'unprepared  to  bear  a  crop  or  even  to  make  satisfactory 
growth  the  next  season. 

Differences  in  fruit  were  as  marked  as  were  differences  in 
foliage.  Liquid-sprayed  trees  gave  smooth  fruit  of  good  size.  Dust- 
sprayed  and  check  trees  gave  small,  ill-formed  fruit,  badly  marked 
by  scab  and  of  very  little  value  even  as  evaporator  stock. 

Dust  spray  is  52  percent  cheaper  than  liquid  spray  and  it  is 
easier  to  transport  about  the  orchard.  It  has  no  other  advantages. 

The  results  of  the  experiments  are  sufficiently  decisive  to  war- 
rant the  conclusion  that  dust  spray  is  absolutely  ineffective  as  a  pre- 
ventive of  injury  from  prevailing  orchard  fungi,  and  that  it  is  con- 
siderably less  efficient  as  an  insect  remedy  than  is  the  liquid  method 
of  applying  arsenites. 

The  effort  of  the  orchardist  may  be  best  expended  in  perfecting 
the  preparation  and  application  of  the  standard  Bordeaux  mixture 
combined  with  arsenites. 


1906.'] 


SPRAYING  APPLES. 


241 


PLATE  8. — WILLOW  TWIG  SPRAYED  six  TIMES  WITH  LIQUID  BORDEAUX 
AND  PARIS  GREEN.    FROM  PHOTGGRAPH  OCTOBER  4,  1905. 


BULLETIN  No.  106. 


[February,  1906. 


PLATE  J).— WILLOW  TWIG  NOT  SPRAYED.     LEAVES  NOW  ON  THIS  TREE 

ARE  ALL  NEW,  FROM  BUDS  THAT  SHOULD  HAVE  REMAINED  DORMANT 

UNTIL  SPRING.    FROM  PHOTOGRAPH  OCTOBER  4,  1905. 


—:          T^q 

«?-( 


